Low power consumption is a major issue in an allocation using a mobile device because the mobile device has a limited power supply.
Many schemes have been suggested for reducing power consumption in a communication system, and a self heterodyne structure using OOK modulation as illustrated in FIG. 1 is suitable for being employed in a mobile device because the self heterodyne structure has a simplified system structure and does not need to include a phase-locked loop circuit which consumes great power, thereby greatly reducing overall power consumption of the system.
FIG. 1 illustrates a transmitter that includes a conventional Gbps high-speed OOK signal modulation device having a bandwidth with a millimeter wave, which can be employed in a general mobile device.
Referring to FIG. 1, a transmitter includes an OOK modulation device 100 and an antenna ANT. The OOK modulation device 100 receives a Gbps OOK data signal and modulates the OOK data signal to output the modulated OOK data signal to the antenna ANT. The antennal ANT transmits an output of the OOK modulation device 100.
The transmitter employing the self heterodyne structure using OOK modulation also transmits a local carrier signal having a frequency of 60 GHz along with the modulated OOK data signal such that a receiver may demodulate the modulated OOK data signal. The OOK modulation device 100 in the transmitter, instead of a general power amplifier, is in conducting state (on state) and transmits the modulated OOK data signal through the antennal ANT when the OOK data signal corresponds to ‘1’, and is in a non-conducting state (off state) and transmits not signal when the OOK data signal corresponds to ‘0’.
The On/off isolation characteristic of the OOK modulation device in response to the on state and off state of OOK input data, the transmission gain of a signal having an on state, power consumption and the data processing speed are important articles when designing an OOK modulation device.
Conventional OOK modulation devices have disadvantages such as low signal transmission gain and a signal leakage due to frequency characteristic and these disadvantages become worse when OOK modulation devices are fabricated using complementary metal oxide semiconductor (CMOS) process for low cost and low power consumption.
Due to these reasons, there is a need for an OOK modulation device having a high on/off isolation characteristic and data processing speed greater than a Gbps value in a millimeter wave range that has a large signal loss and a large signal leakage.
Korean Patent Publication No. 10-2012-0038275 published on Apr. 23, 2012, discloses an OOK modulation device that outputs a high-power level OOK modulation signal. The OOK modulation device includes a plurality of amplifiers and one amplifier operates as a common source amplifier in response to an amplified signal of another amplifier. The OOK modulation device includes an oscillator that generates an carrier wave having a high frequency. Due to the high frequency, the oscillator consumes great power and the OOK modulation device must include an additional circuitry such as a buffer.